1. Field of the Invention
The present invention relates to a hose for lining pressure pipe lines.
2. Description of Related Art
From German Printed Publication 34 14 531 C3, a lining material in the form of a hose and destined for pipe lines has become known. The lining material includes a textile shell of warp threads and woof threads, which is provided with a coating made from a flexible synthetic resin. The lining material is, together with a cement on its inner surface, introduced into a pipe line and moved in forward direction inside the pipe line, in which case it will be turned over under the influence of a pressure medium so that the cement comes between the lining material and the inside wall of the pipe line. In order to enable adaptation of the lining material to pipe lines of relatively small internal diameter and sharper curvatures, warp threads of an elastic yarn are used, with a synthetic yarn or synthetic yarns being wound around the same over its entire length. Hereby, a high stretching ability in the longitudinal direction is obtained so that, e.g., formation of creases in the region of the curvatures is avoided. The woof threads may also consist of an elastic yarn, a synthetic yarn being wound around in the same manner over its entire length. Hereby, a good adaptation to varying internal diameters of the pipe lines is made possible.
In German Printed Publication 35 05 107 C2, the aforementioned lining material is described as being disadvantageous since it requires an elastic polyurethane yarn which is relatively expensive and which is not suited for larger hose diameters. In order to enable the use of such a lining material in pipe lines of sharper curvatures and of relatively large internal diameters, it, therefore, is suggested to make the warp threads from rippled yarns of polybutylene terephthalate fibers and the woof threads from a yarn of synthetic fibers, in which case the woof threads, possibly, likewise consist of rippled yarn.
Such linings in the form of hoses and destined for pipe lines must usually be of great strength in the longitudinal direction. Only in the longitudinal direction are the pipe lines commonly subjected to high mechanical strains, e.g., by weighing-down of the ground in which the pipe lines ar buried. In contrast thereto, the hoses produced with a specific undersized diameter, as compared to the pipe lines, must, in a transverse direction, radially expand and bear on the inside wall of the pipe under an internal pressure. The internal pressure which is maintained until setting of the cement shall, therewith, be as low as possible in order that the cement not be squeezed into lateral pipe outlets whereby, on the one hand, bonding of the lining to the pipe inside wall is affected and, on the other hand, subterranean gating of the pipe outlets, i.e., tapping the outlets out of the pipe line, is rendered more difficult or even impossible. Furthermore, the turn-over operation has to be carried out such that the risk of damaging the lining is small and that, moreover, only a low transport pressure is required, whereby the operation can be better controlled.